1. Field of the Invention
The present invention relates to a check valve and, more particularly, to a check valve for use in a pump of a hydraulic cylinder that may prevent the hydraulic oil from leakage during the accelerated operation of the jack.
2. Description of the Prior Arts
The cylinder is an indispensable component provided in jacks due to its high bearing capacity, thus lifting objects easily. However, the conventional cylinder had some disadvantages, such as poor operating stability, slow raising speed and the like. To overcome such defects, an improved cylinder provided with an air operated pump therein had been developed and applied in the related field.
Such an improved air-operated pump utilizes an inputted air pressure to actuate a piston (including a spring element disposed therein and designed in an air venting and a position returning manner). A stem member of the piston is in communication with an oil route of the cylinder so as to cause a pump effect. Thus, the cylinder may generate larger fluid pressure during the operation of the air operated pump for enhancing the operating speed. Thereby, the lifting speed of the jack may be improved. However, such a lifting speed still can be accelerated.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.